SARS-CoV-2 virus emerged as a novel human pathogen and it could cause a range of different clinical outcomes in general population. The project clinical study will focus on the susceptibility of people to SARS-CoV-2 infection, the severity of the COVID-19 disease, the patients’ clinical improvement and the mortality in patients with COVID-19. The main study outcomes will be dichotomized and, therefore, the primary statistical analysis will be based on univariable and multivariable binary logistic regression.
The determination of susceptibility for SARS-CoV-2 infection will require inclusion of healthy and infected subjects which will contribute to the whole study population. The people with asymptomatic infection or those with any clinical features of COVID-19 disease will be allocated to the infected subjects study arm.
Severity of COVID-19 disease will be staged in the following categories: mild (any signs and symptoms of COVID-19 without viral pneumonia or hypoxia), moderate (pneumonia), severe (severe pneumonia) and critical illness (acute respiratory distress syndrome, sepsis, septic shock, acute thrombosis). The severity of disease will be categorized on mild (mild disease and moderate pneumonia) and severe cases (severe pneumonia and critical illness).
Patients’ clinical improvement will be assessed according to the recommendations of World Health Organization using Ordinal Scale for Clinical Improvement, up to 6 weeks from recruitment to hospital discharge or death. The patient’s status will be scored from 0 (uninfected) to 9 (death) and it will supplement the case allocation to mild (4 score) and severe (≥5 score) disease.
Mortality from COVID-19 will be determined as the number of participants which had fatal outcome up to 6 weeks from recruitment into the study, including the hospital treatment period. Case fatality ratio will be calculated as the proportion of patients who died from all causes (all-cause mortality) in relation to the total number of patients.
